Work vehicles, such as agricultural, construction or forestry work vehicles, typically include an internal combustion engine which drives a transmission, which in turn drives at least one axle through a differential lock. In the event that traction is lost and a wheel begins to slip, all power is applied to the slipping wheel through the differential and the opposite wheel receives little or no torque. In the case of a rear wheel drive work vehicle, an operator can typically lock the rear wheels together by operating a foot or hand lever to engage the differential lock. By engaging the differential lock, the wheels spin at the same speed and the wheel that is not spinning can be used to regain traction.
The assignee of the present invention, John Deere, also manufactures and sells a front wheel assist work vehicle used primarily in the construction and agricultural markets (also known as a mechanical front wheel drive, or MFWD). With an MFWD, the front wheels are typically locked together through a differential using an electric switch on the floor.
Certain types of work vehicles, such as front end loaders, may be used to push earth or the like, resulting in a load which could cause wheel slippage. Another example is an agricultural tractor pulling a pull-type implement through wet soil, in which event the drive wheels could also slip. Under such conditions, it may be desirable to automatically engage the differential lock of the rear and/or front differentials without operator intervention, thereby allowing the operator to focus on the work operation at hand.
What is needed in the art is a method of automatically engaging a differential lock in a work vehicle upon accurate detection of wheel slippage of one or more axles.